In general, carriers are utilized for transporting and/or storing batches of silicon wafers or magnetic disks before, during and after processing of the disks or wafers. The wafers can be processed into integrated circuits and the disks can be processed into a magnetic storage disks for computers. The terms wafer, disk, or substrate are used interchangeably herein and any of these terms can refer to semiconductor wafers, magnetic discs, flat panel substrates, and other such substrates, unless otherwise indicated.
The processing of wafer disks into integrated circuit chips often involves multiple steps where the disks are processed at various processing stations, and stored and transported between processing steps. Due to the delicate nature of the disks and their susceptibility to contamination by particles or chemicals, it is vital that they are properly protected throughout this procedure. Wafer containers have been used to provide this necessary protection. Additionally, since the processing of disks is generally automated, it is necessary for disks to be precisely positioned relative to the processing equipment for the robotic removal and insertion of the wafers. A second purpose of a wafer container is to securely hold the wafer disks during transport. The terms wafer containers, carriers, cassettes, transport/storage bins, and the like, are used interchangeably herein unless otherwise indicated.
During processing of semiconductor wafers or magnetic disks, the presence of or generation of particulates presents very significant contamination problems. Contamination is accepted as the single largest cause of yield loss in the semi-conductor industry. As the size of integrated circuitry has continued to be reduced, the size of particles which can contaminate an integrated circuit has also become smaller making minimization of contaminants all the more critical. Contaminants in the form of particles may be generated by abrasion such as the rubbing or scraping of the carrier with the wafers or disks, with the carrier covers or enclosures, with storage racks, with other carriers or with processing equipment. Additionally, particulates such as dust can be introduced into the enclosures through the openings or joints in the covers and/or enclosures. Thus, a critical function of wafer carriers is to protect the wafers therein from such contaminants.
Containers are generally configured to axially arrange the wafers or disks in slots, and to support the wafers or disks in slots, and to support the wafers or disks by or near their peripheral edges. The wafers or disks are conventionally removable from the containers in a radial direction upwardly or laterally. The containers may have a shell portion with a lower opening, a door to latch into the lower opening, and a discrete carrier that rests on the door. This configuration, known as SMIF pods, is illustrated in U.S. Pat. Nos. 4,995,430 and 4,815,912, both owned by the owner of the instant application and both incorporated herein by reference. Additionally, wafer carrier assemblies can have front openings with doors that latch onto front openings, which are known as FOUPs or FOSBs, and are described in, for example, U.S. Pat. Nos. 6,354,601, 5,788,082 and 6,010,008, all of which are incorporated by reference herein. In certain configurations, the bottom covers or doors, front doors or the container portions have been provided with openings or passageways to facilitate the introduction and/or exhaustion of gases such as nitrogen or other purified gasses, into the wafer carrier assemblies to displace ambient air that might have contaminants.
Previous containers have employed filter plugs to reduce the amount of particular contaminants that enter the container assemblies during purging. However, conventional attachment and sealing between the operation element, i.e. the filter, and the housing of the seal is by the way of rigid plastic housings and o-rings. Wafer containers known in the art have also utilized various connection or coupling mechanisms for fluidly interfacing the flow passageways of the wafer containers to fluid supply and pressure or vacuum sources. Such attachment and sealing requires specialized components which may be of complex configuration.